A High Court ruling on the retention and use of mobile phone data, which boosts Graham Dwyer's bid to appeal against his murder conviction, is to be appealed by the State.

The High Court heard today that the Garda Commissioner and other State defendants in the action would be seeking a "leapfrog" appeal to the Supreme Court.

Last month’s ruling was significant for Foxrock-based architect Dwyer (46), who plans to challenge his conviction for the murder of childcare worker Elaine O’Hara in the Court of Appeal.

Mobile phone data obtained by gardaí had a large bearing on the investigation of her murder.

But Mr Justice Tony O’Connor found the provisions set out in Section 6 of the 2011 Communications Act, which allowed gardaí of chief superintendent rank and above to request user data from telecommunications providers, contravened EU law and the European Convention on Human Rights.

Mr Justice O’Connor found that the retention of data was general and indiscriminate. He said there was no prior review by a court or an independent administrative authority for access to data and no adequate legislative guarantees against abuse of such data.

Today, Mr Justice O'Connor heard both sides consented to a stay being put on declarations arising from his ruling taking effect until the determination of the appeal.

Earlier, Remy Farrell SC, counsel for Dwyer, told the court his client had brought the proceedings “on a defined point and for a limited purpose”.

He said his client intended to argue against the retention and access of data in his conviction appeal.

While last month’s ruling could potentially have implications not just for Dwyer’s appeal, but other criminal cases as well, it does not automatically mean that any convictions will be quashed.

In his ruling last month, Mr Justice O’Connor said Dwyer would be obliged, in his appeal, to address rules regarding admissibility of evidence.

The judge referred to a Supreme Court case know as JC, which related to the admissibility of evidence. In that case the Supreme Court ruled that evidence obtained in breach of an accused’s constitutional rights does not necessarily have to be excluded at trial if the breach involved was not conscious and deliberate.

Dwyer met 36-year-old Elaine O’Hara online. She disappeared in August 2012 and her remains were found in September 2013 in a forest at Killakee in the Dublin Mountains.

In his trial, the prosecution argued Dwyer stabbed his victim to death for his own sexual gratification.